Penicillium pinophilum—A novel microorganism for nutrient management in pomegranate (Punica granatum L.)

• Perhaps first report on solubilization of insoluble K minerals by Penicillium pinophilum
• P. pinophilum along with insoluble K increases N, P and K uptake by plants.
• P. pinophilum promotes plant growth and physiological activities of pomegranate.
• P. pinophilum enhances effectiveness of K-feldspar as K-fertilizer.

This study involves isolation, identification and evaluation of the most efficient fungal stain that promotes the plant growth and nutrient uptake in pomegranate in semi-arid agro-ecosystem. Five Penicillium strains were isolated from rhizosphere and evaluated in vitro for their K and P solubilizing efficacy and specific accession numbers were obtained from the National Fungal Collection Centre of India (NFCCI). The best performing strain was identified as Penicillium pinophilum (NFCCI 2498) using DNA sequencing. A pot culture experiment was conducted to evaluate the effectiveness of P. pinophilum strain alone or in combination with insoluble K on growth and nutrient uptake of pomegranate plants. Soil inoculation with P. pinophilum was found to increase nutrient uptake (N, P, and K) that resulted in improved growth, significantly higher leaf area index and photosynthetic rate of plant. Inoculation of P. pinophilum with the insoluble K treated (100 mg K kg−1 soil) soil exhibited increased potassium and phosphorus uptake by 47.47 and 63.44 per cent, respectively. Mobilization of insoluble P could be attributed to the development and colonization of P. pinophilum in and around the rhizosphere of pomegranate as evidenced by higher dehydrogenase, alkaline and acid phosphatase activity in inoculated soil than control.